In the baking of a pizza made with natural mozzarella cheese, it is desired that the cheese go through a number of transformations. The cheese melts; some of the unbound water in the cheese is evaporated; some of the milkfat separates ("oils off"); and some of the protein browns and blisters. Each of these transformations has to occur in moderation to obtain a commercially acceptable product. Also, the baked cheese must have a chewy, stringy texture and consistency, with no off-flavor components. In addition, during baking, the moisture release from the cheese must be controlled to achieve desired cooking characteristics.
Natural mozzarella cheeses can vary in moisture and milkfat content, e.g., within the ranges of about 45 to 60 percent moisture and about 16 to 25 percent milkfat (wet basis). The moisture includes both bound and unbound water (sometimes called "free moisture") and is measured as the percent of weight lost when the cheese is dried overnight in a 200.degree. C. oven. "Wet milkfat" content refers to the percentage of milkfat based on the weight of the entire cheese, not just the solids. The milkfat content of mozzarella also can be reported as "fat on dry basis" (or FDB), which is the percent milkfat based on the weight of dried solids in the cheese.
The ratio of unbound water to bound water in mozzarella can vary. By "unbound water" is meant the moisture that is not chemically or physically bound in the cheese. The molecular structure of the protein can vary also, depending on the extent of proteolysis the cheese has undergone.
Different mozzarella cheeses bake best at different oven temperatures and/or in different types of ovens. Oven temperatures used to bake pizzas range from about 400.degree. F. to about 1,000.degree. F. Among the different ovens employed are deck ovens, impingement ovens, and infrared ovens.
A deck oven is a type of oven that uses radiant and conductive heat. Older style pizza ovens are typically deck ovens.
An impingement oven is a type of oven that uses mostly convection to heat the pizza, as well as some heat of conduction. The newer pizza ovens typically are of the impingement type. Some pass the pizzas through on conveyors.
A radiant oven is a type in which the pizza is baked by radiant heat.
The growth of the pizza industry has resulted in a variety of styles of pizzas (i.e., pan pizza, thin pizzas, etc.) and a variety of means to bake such pizzas (i.e., deck ovens, impingement ovens, etc.) The mozzarella that will perform acceptably under one set of conditions often is different (in terms of moisture or fat content, protein composition, etc.) from the mozzarella that will perform acceptably under a different set of conditions. To satisfy this diversity, it has been necessary to manufacture a wide variety of mozzarella cheeses of varying chemical compositions, aging requirements, etc., to meet desired baking characteristics (i.e., browning, meltdown, fat release, and blistering.) It would be an advance in the technology if a way could be found to modify a basic mozzarella to alter its baking characteristics, so that it could satisfactorily serve in at least two different environments: one when it is unmodified, the other when it is modified.